Abstract
The pathway used by a dispersing population influences its level of genetic diversity in its new range. Extreme long-distance dispersal typically results in founding populations with genetic struc~e that does not fully represent the source population and with little to no additional gene flow from the source population (Wilson et al. 2008). Several (5-30) black spiny-tailed iguanas (Ctenosaura simi/is) that are native to neotropical Mexico and Central America were introduced to Keewaydin Island (Krysko et al. 2003), a barrier island in Collier County, Florida, in 1995. The population has since expanded from the initial introduction site. One major goal of this project was to determine if this introduced population possesses low genetic diversity consistent with its form of introduction. A second major goal was to suggest a source location for this introduced population based on haplotype matching. C. simi/is specimens (n ,; 21) of different sexes and age classes were collected from three out of five survey sites on Keewaydin Island. Muscle tissue was removed from each specimen, mitochondrial DNA was extracted, and a region ofthe ND4 gene was amplified (after Zarza et al. 2008) and sequenced (Eurofins MWG Operon). Haplotype quantification and nucleotide diversity were investigated using pairwise genetic distance in MEGA. Two cladograms were constructed with the maximum parsimony and maximum likelihood techniques, respectively, to investigate genetic relationships within and among Ctenosaura species. All sequences derived from C. simi/is specimens from Keewaydin Island were identical, meaning diversity at this genetic locus was zero. These C. similis individuals likely descended from a single maternal lineage. The sequence discovered on Keewaydin Island matched a haplotype from Honduras, which suggests Honduras as a possible source location. Results of this study have important implications for understanding the mechanisms of successful invasions for diverse species. This study of an extreme longdistance dispersal event demonstrates that small founder group size and low genetic diversity may not inevitably result in a failed introduction.
